Grasping for tissue repair

ABSTRACT

The invention provides improved devices, systems, and methods for tissue approximation and repair at treatment sites. The invention provides devices, systems, and methods that may more successfully approximate and repair tissue by improving the capture of tissue into the devices. The invention may be a one-way mechanism that allows tissue to enter the mechanism but not easily exit, such as a leaf-spring, a protrusion, a pivoting arm and one or more frictional elements.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 16/748,450, filed on Jan. 21, 2020, which is acontinuation application of U.S. patent application Ser. No. 16/241,647,filed on Jan. 7, 2019, which is a continuation application of U.S.patent application Ser. No. 14/577,852, filed on Dec. 19, 2014, issuedas U.S. Pat. No. 10,188,392, the entire contents of which areincorporated herein by reference.

BACKGROUND

The present invention relates generally to medical methods, devices, andsystems. In particular, the present invention relates to methods,devices, and systems for the endovascular, percutaneous, or minimallyinvasive surgical treatment of bodily tissues, such as tissueapproximation or valve repair. More particularly, the present inventionrelates to repairing heart valves and venous valves, and devices andmethods for removing or disabling mitral valve repair components throughminimally invasive procedures.

Surgical repair of bodily tissues often involves tissue approximationand fastening of such tissues in the approximated arrangement. Whenrepairing valves, tissue approximation includes coapting the leaflets ofthe valves in a therapeutic arrangement which may then be maintained byfastening or fixing the leaflets. Such coaptation can be used to treatregurgitation which most commonly occurs in the mitral valve.

Mitral valve regurgitation is characterized by retrograde flow from theleft ventricle of a heart through an incompetent mitral valve into theleft atrium. During a normal cycle of heart contraction (systole), themitral valve acts as a check valve to prevent oxygenated blood fromflowing back into the left atrium. In this way, oxygenated blood ispumped into the aorta through the aortic valve. Mitral valveregurgitation can significantly decrease the pumping efficiency of theheart, placing the patient at risk of severe, progressive heart failure.Mitral valve regurgitation can result from a number of differentmechanical defects in the mitral valve or the left ventricular wall. Thevalve leaflets, the valve chordae which connect the leaflets to thepapillary muscles, the papillary muscles themselves, or the leftventricular wall may be damaged or otherwise dysfunctional. Commonly,the valve annulus may be damaged, dilated, or weakened, limiting theability of the mitral valve to close adequately against the highpressures of the left ventricle.

The most common treatments for mitral valve regurgitation rely on valvereplacement or repair including leaflet and annulus remodeling, thelatter generally referred to as valve annuloplasty. One technique formitral valve repair which relies on suturing adjacent segments of theopposed valve leaflets together is referred to as the “bow-tie” or“edge-to-edge” technique. While all these techniques can be effective,they usually rely on open heart surgery where the patient's chest isopened, typically via a sternotomy, and the patient placed oncardiopulmonary bypass. The need to both open the chest and place thepatient on bypass is traumatic and has associated high mortality andmorbidity.

In some patients, a fixation device can be installed into the heartusing minimally invasive techniques. The fixation device can hold theadjacent segments of the opposed valve leaflets together and may reducemitral valve regurgitation. One such device used to clip the anteriorand posterior leaflets of the mitral valve together is the MitraClip®fixation device, sold by Abbott Vascular, Santa Clara, Calif., USA.

DESCRIPTION OF THE BACKGROUND ART

Many techniques exist for approximating and repairing tissues and organsat treatment sites. For example, minimally invasive and percutaneoustechniques for coapting and modifying mitral valve leaflets to treatmitral valve regurgitation are described in PCT Publication Nos. WO98/35638; WO 99/00059; WO 99/01377; and WO 00/03759; WO 2000/060995; WO2004/103162. Maisano et al. (1998) Eur. J. Cardiothorac. Surg.13:240-246; Fucci et al. (1995) Eur. J. Cardiothorac. Surg. 9:621-627;and Umana et al. (1998) Ann. Thorac. Surg. 66:1640-1646, describe opensurgical procedures for performing “edge-to-edge” or “bow-tie” mitralvalve repair where edges of the opposed valve leaflets are suturedtogether to lessen regurgitation. Dec and Fuster (1994) N. Engl. J. Med.331:1564-1575 and Alvarez et al. (1996) J. Thorac. Cardiovasc. Surg.112:238-247 are review articles discussing the nature of and treatmentsfor dilated cardiomyopathy.

Mitral valve annuloplasty is described in the following publications:Bach and Bolling (1996) Am. J. Cardiol. 78:966-969; Kameda et al. (1996)Ann. Thorac. Surg. 61:1829-1832; Bach and Bolling (1995) Am. Heart J.129:1165-1170; and Bolling et al. (1995) 109:676-683. Linear segmentalannuloplasty for mitral valve repair is described in Ricchi et al.(1997) Ann. Thorac. Surg. 63:1805-1806. Tricuspid valve annuloplasty isdescribed in McCarthy and Cosgrove (1997) Ann. Thorac. Surg. 64:267-268;Tager et al. (1998) Am. J. Cardiol. 81:1013-1016; and Abe et al. (1989)Ann. Thorac. Surg. 48:670-676.

Percutaneous transluminal cardiac repair procedures are described inPark et al. (1978) Circulation 58:600-608; Uchida et al. (1991) Am.Heart J. 121: 1221-1224; and Ali Khan et al. (1991) Cathet. Cardiovasc.Diagn. 23:257-262. Endovascular cardiac valve replacement is describedin U.S. Pat. Nos. 5,840,081; 5,411,552; 5,554,185; 5,332,402; 4,994,077;and 4,056,854. U.S. Pat. No. 3,671,979 describes a catheter fortemporary placement of an artificial heart valve.

Other percutaneous and endovascular cardiac repair procedures aredescribed in U.S. Pat. Nos. 4,917,089; 4,484,579; and 3,874,338; and PCTPublication No. WO 91/01689.

Thoracoscopic and other minimally invasive heart valve repair andreplacement procedures are described in U.S. Pat. Nos. 5,855,614;5,829,447; 5,823,956; 5,797,960; 5,769,812; and 5,718,725.

BRIEF SUMMARY

The present disclosure describes devices intended for intravasculardelivery and for use in treating mitral valve defects in human patients.The mitral valve of a human heart has an atrial side, a ventricularside, an anterior leaflet, a posterior leaflet, and an opening betweenthe leaflets.

In one embodiment, the device can include a body, a pair of proximalelements, and a pair of distal elements. Each proximal element iscoupled at a first end to the body on opposite sides of the body, andhas a free second end. Each proximal element has a proximal engagementsurface between its first and second ends. Each proximal engagementsurface is configured to approximate and engage a portion of theleaflets adjacent the mitral valve on the atrial side.

Each proximal engagement surface also has a proximal retaining elementconfigured to permit tissue to move toward the first end of the proximalelement and to resist movement of the tissue away from the first end ofthe proximal element.

Each distal element is pivotally coupled at a first end to the body onopposite sides of the body, and has a free second end. Each distalelement has a distal engagement surface between its first and secondends. Each distal engagement surface is configured to approximate andengage a portion of the leaflets adjacent the mitral valve on theventricular side.

A first one of the proximal elements cooperates with a first one of thedistal elements to form a space for receiving a portion of the anteriorleaflet therebetween. A second one of the proximal elements cooperateswith a second one of the distal elements to form a space for receiving aportion of the posterior leaflet therebetween. Each such space has anopen end and a closed end, and the closed end forms an apex.

The device includes an actuator for selectively moving the distalelements between a first position in which the distal elements are in acollapsed, low profile configuration for delivery of the device, asecond position in which the distal elements are in an expandedconfiguration for positioning the device relative to the mitral valve,and a third position in which the distal elements are secured inposition against a portion of the leaflets adjacent the mitral valve onthe ventricular side.

The device also includes an actuator for selectively moving the proximalelements between a first position in which the proximal elements are ina collapsed, low profile configuration for delivery of the device and asecond position in which the proximal elements are in an expandedconfiguration for engaging a portion of the leaflets adjacent the mitralvalve on the atrial side. Each distal element can also include a distalretaining element positioned along the distal engagement surface. Eachdistal retaining element is configured to cooperate with a correspondingproximal retaining element to capture a free edge of the mitral valveleaflet as the device is positioned relative to the mitral valve. Eachretaining element can be configured to cooperate with a frictionalelement to allow a leading free edge of the leaflets to move in a firstdirection toward the body with little or no resistance or restrictionand to resist or prevent movement of the free edge of the leaflets in anopposite direction away from the body.

These and other objects and features of the present disclosure willbecome more fully apparent from the following description and appendedclaims, or may be learned by the practice of the embodiments of theinvention as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the above and other advantages and features of thepresent disclosure, a more particular description of the invention willbe rendered by reference to specific embodiments thereof which areillustrated in the appended drawings. It is appreciated that thesedrawings depict only illustrated embodiments of the invention and aretherefore not to be considered limiting of its scope. Embodiments of theinvention will be described and explained with additional specificityand detail through the use of the accompanying drawings in which:

FIG. 1 illustrates free edges of leaflets of the mitral valve in normalcoaptation, and FIG. 2 illustrates the free edges in regurgitativecoaptation.

FIGS. 3A-3C illustrate grasping of the leaflets with a fixation device,inversion of the distal elements of the fixation device and removal ofthe fixation device, respectively.

FIG. 4 illustrates the fixation device in a desired orientation relativeto the leaflets.

FIG. 5 illustrates an exemplary fixation device coupled to a shaft.

FIGS. 6A-6B, 7A-7B, and 8 illustrate a fixation device in variouspossible positions during introduction and placement of the devicewithin the body to perform a therapeutic procedure.

FIGS. 9A-9B illustrate a fixation device embodiment with a leaf spring.

FIG. 10 illustrates a close-up of a portion of another embodiment of afixation device.

FIG. 11A illustrates a close-up of a portion of another embodiment of afixation device.

FIGS. 11B and 11C each illustrate a close-up cross-sectional side viewof a portion of another embodiment of a fixation device.

FIGS. 11D and 11E each illustrate a close-up cross-sectional transverseview of a portion of another embodiment of a fixation device.

FIG. 12 illustrates a close-up of a portion of another embodiment of afixation device.

DETAILED DESCRIPTION

I. INTRODUCTION

-   -   A. Cardiac Physiology

As shown in FIG. 1, the mitral valve (MV) comprises a pair of leaflets(LF) having free edges (FE) which, in patients with normal heartstructure and function, meet evenly to close along a line of coaptation(C). The leaflets (LF) attach to the surrounding heart structure alongan annular region called the annulus (AN). The free edges (FE) of theleaflets (LF) are secured to the lower portions of the left ventricle LVthrough chordae tendinae (or “chordae”).

As the left ventricle of a heart contracts (which is called “systole”),blood flow from the left ventricle to the left atrium through the mitralvalve (MV) (called “mitral regurgitation”) is usually prevented by themitral valve.

Regurgitation occurs when the valve leaflets do not close properly andallow leakage from the left ventricle into the left atrium. A number ofheart structural defects can cause mitral regurgitation. FIG. 2 shows amitral valve with a defect causing regurgitation through a gap (G).

II. GENERAL OVERVIEW OF MITRAL VALVE FIXATION TECHNOLOGY

Several methods for repairing or replacing a defective mitral valveexist. Some defects in the mitral valve can be treated throughintravascular procedures, where interventional tools and devices areintroduced and removed from the heart through the blood vessels. Onemethod of repairing certain mitral valve defects includes intravasculardelivery of a fixation device to hold portions of the mitral valvetissues in a certain position. One or more interventional catheters maybe used to deliver a fixation device to the mitral valve and install itthere as an implant to treat mitral regurgitation.

FIG. 3A illustrates a schematic of an interventional tool 10 with adelivery shaft 12 and a fixation device 14. The tool 10 has approachedthe mitral valve MV from the atrial side and grasped the leaflets LF.

The fixation device 14 is releasably attached to the shaft 12 of theinterventional tool 10 at the distal end of the shaft 12. In thisapplication, when describing devices, “proximal” means the directiontoward the end of the device to be manipulated by the user outside thepatient's body, and “distal” means the direction toward the working endof the device that is positioned at the treatment site and away from theuser. When describing the mitral valve, proximal means the atrial sideof the leaflets and distal means the ventricular side of the leaflets.

The fixation device 14 comprises proximal elements 16 and distalelements 18 which protrude radially outward and are positionable onopposite sides of the leaflets LF as shown so as to capture or retainthe leaflets therebetween. The fixation device 14 is coupleable to theshaft 12 by a coupling mechanism 17.

FIG. 3B illustrates that the distal elements 18 may be moved in thedirection of arrows 40 to an inverted position. The proximal elements 16may be raised as shown in FIG. 3C. In the inverted position, the device14 may be repositioned and then be reverted to a grasping positionagainst the leaflets as in FIG. 3A. Or, the fixation device 14 may bewithdrawn (indicated by arrow 42) from the leaflets as shown in FIG. 3C.Such inversion reduces trauma to the leaflets and minimizes anyentanglement of the device with surrounding tissues.

FIG. 4 illustrates the fixation device 14 in a desired orientation inrelation to the leaflets LF. The mitral valve MV is viewed from theatrial side, so the proximal elements 16 are shown in solid line and thedistal elements 18 are shown in dashed line. The proximal and distalelements 16, 18 are positioned to be substantially perpendicular to theline of coaptation C. During diastole (when blood is flowing from theleft atrium to the left ventricle), fixation device 14 holds theleaflets LF in position between the elements 16, 18 surrounded byopenings or orifices O which result from the diastolic pressuregradient, as shown in FIG. 4.

Once the leaflets are coapted in the desired arrangement, the fixationdevice 14 is detached from the shaft 12 and left behind as an implant.

-   -   A. Exemplary Fixation Device

FIG. 5 illustrates an exemplary fixation device 14. The fixation device14 is shown coupled to a shaft 12 to form an interventional tool 10. Thefixation device 14 includes a coupling member 19, a pair of opposedproximal elements 16, and a pair of opposed distal elements 18. Thedistal elements 18 comprise elongate arms 53, each arm having a proximalend 52 rotatably connected to the coupling member 19 and a free end 54.Preferably, each free end 54 defines a curvature about two axes, axis 66perpendicular to longitudinal axis of arms 53, and axis 67 perpendicularto axis 66 or the longitudinal axis of arms 53.

Arms 53 have engagement surfaces 50. Arms 53 and engagement surfaces 50are configured to engage about 4-10 mm of tissue, and preferably about6-8 mm along the longitudinal axis of arms 53. Arms 53 further include aplurality of openings.

The proximal elements 16 are preferably resiliently biased toward thedistal elements 18. When the fixation device 14 is in the open position,each proximal element 16 is separated from the engagement surface 50near the proximal end 52 of arm 53 and slopes toward the engagementsurface 50 near the free end 54 with the free end of the proximalelement 16 contacting engagement surface 50, as illustrated in FIG. 5.

Proximal elements 16 include a plurality of openings 63 and scallopedside edges 61 to increase their grip on tissue. The proximal elements 16optionally include a frictional element or multiple frictional elementsto assist in grasping the leaflets. The frictional elements may comprisebarbs 60 having tapering pointed tips extending toward engagementsurfaces 50. Any suitable frictional elements may be used, such asprongs, windings, bands, barbs, grooves, channels, bumps, surfaceroughening, sintering, high-friction pads, coverings, coatings or acombination of these.

The proximal elements 16 may be covered with a fabric or other flexiblematerial. Preferably, when fabrics or coverings are used in combinationwith barbs or other frictional features, such features will protrudethrough such fabric or other covering so as to contact any tissueengaged by proximal elements 16.

The fixation device 14 also includes an actuator or actuation mechanism58. The actuation mechanism 58 comprises two link members or legs 68,each leg 68 having a first end 70 which is rotatably joined with one ofthe distal elements 18 at a riveted joint 76 and a second end 72 whichis rotatably joined with a stud 74. The actuation mechanism 58 comprisestwo legs 68 which are each movably coupled to a base 69. Or, each leg 68may be individually attached to the stud 74 by a separate rivet or pin.The stud 74 is joinable with an actuator rod which extends through theshaft 12 and is axially extendable and retractable to move the stud 74and therefore the legs 68 which rotate the distal elements 18 betweenclosed, open and inverted positions. Immobilization of the stud 74 holdsthe legs 68 in place and therefore holds the distal elements 18 in adesired position. The stud 74 may also be locked in place by a lockingfeature. This actuator rod and stud assembly may be considered a firstmeans for selectively moving the distal elements between a firstposition in which the distal elements are in a collapsed, low profileconfiguration for delivery of the device, a second position in which thedistal elements are in an expanded configuration for positioning thedevice relative to the mitral valve, and a third position in which thedistal elements are secured in position against a portion of theleaflets adjacent the mitral valve on the ventricular side.

FIGS. 6A-6B, 7A-7B, and 8 illustrate various possible positions of thefixation device 14 of FIG. 5. FIG. 6A illustrates an interventional tool10 delivered through a catheter 86. The catheter 86 may take the form ofa guide catheter or sheath. The interventional tool 10 comprises afixation device 14 coupled to a shaft 12 and the fixation device 14 isshown in the closed position.

FIG. 6B illustrates a device similar to the device of FIG. 6A in alarger view. In the closed position, the opposed pair of distal elements18 are positioned so that the engagement surfaces 50 face each other.Each distal element 18 comprises an elongate arm 53 having a cupped orconcave shape so that together the arms 53 surround the shaft 12. Thisprovides a low profile for the fixation device 14.

FIGS. 7A-7B illustrate the fixation device 14 in the open position. Inthe open position, the distal elements 18 are rotated so that theengagement surfaces 50 face a first direction. Distal advancement of theactuator rod relative to shaft 12, and thus distal advancement of thestud 74 relative to coupling member 19, applies force to the distalelements 18 which begin to rotate around joints 76. Such rotation andmovement of the distal elements 18 radially outward causes rotation ofthe legs 68 about joints 80 so that the legs 68 are directed slightlyoutwards. The stud 74 may be advanced to any desired distancecorrelating to a desired separation of the distal elements 18. In theopen position, engagement surfaces 50 are disposed at an acute anglerelative to shaft 12, and are preferably at an angle of between 90 and180 degrees relative to each other. In the open position, the free ends54 of arms 53 may have a span therebetween of about 10-20 mm, usuallyabout 12-18 mm, and preferably about 14-16 mm.

Proximal elements 16 are typically biased outwardly toward arms 53. Theproximal elements 16 may be moved inwardly toward the shaft 12 and heldagainst the shaft 12 with the aid of proximal element lines 90 which canbe in the form of sutures, wires, nitinol wire, rods, cables, polymericlines, or other suitable structures. The proximal element lines 90extend through the shaft 302 of the delivery catheter 300 and connectwith the proximal elements 16. The proximal elements 16 are raised andlowered by manipulation of the proximal element lines 90. Once thedevice is properly positioned and deployed, the proximal element linescan be removed by withdrawing them through the catheter and out theproximal end of the device 10. The proximal element lines 90 may beconsidered a second means for selectively moving the proximal elementsbetween a first position in which the proximal elements are in acollapsed, low profile configuration for delivery of the device and asecond position in which the proximal elements are in an expandedconfiguration for engaging a portion of the leaflets adjacent the mitralvalve on the atrial side.

In the open position, the fixation device 14 can engage the tissue whichis to be approximated or treated. The interventional tool 10 is advancedthrough the mitral valve from the left atrium to the left ventricle. Thedistal elements 18 are then deployed by advancing actuator rod relativeto shaft 12 to thereby reorient distal elements 18 to be perpendicularto the line of coaptation. The entire assembly is then withdrawnproximally and positioned so that the engagement surfaces 50 contact theventricular surface of the valve leaflets, thereby engaging the leftventricle side surfaces of the leaflets. The proximal elements 16 remainon the atrial side of the valve leaflets so that the leaflets liebetween the proximal and distal elements. The interventional tool 10 maybe repeatedly manipulated to reposition the fixation device 14 so thatthe leaflets are properly contacted or grasped at a desired location.Repositioning is achieved with the fixation device in the open position.In some instances, regurgitation may also be checked while the device 14is in the open position. If regurgitation is not satisfactorily reduced,the device may be repositioned and regurgitation checked again until thedesired results are achieved.

It may also be desired to invert distal elements 18 of the fixationdevice 14 to aid in repositioning or removal of the fixation device 14.FIG. 8 illustrates the fixation device 14 in the inverted position. Byfurther advancement of actuator rod relative to shaft 12, and thus stud74 relative to coupling member 19, the distal elements 18 are furtherrotated so that the engagement surfaces 50 face outwardly and free ends54 point distally, with each arm 53 forming an obtuse angle relative toshaft 12.

The angle between arms 53 when the device is inverted is preferably inthe range of about 270 to 360 degrees. Further advancement of the stud74 further rotates the distal elements 18 around joints 76. Thisrotation and movement of the distal elements 18 radially outward causesrotation of the legs 68 about joints 80 so that the legs 68 are returnedtoward their initial position, generally parallel to each other. Thestud 74 may be advanced to any desired distance correlating to a desiredinversion of the distal elements 18. Preferably, in the fully invertedposition, the span between free ends 54 is no more than about 20 mm,usually less than about 16 mm, and preferably about 12-14 mm. Barbs 60are angled slightly in the distal direction (away from the free ends ofthe proximal elements 16), reducing the risk that the barbs will catchon or lacerate tissue as the fixation device is withdrawn.

Once the distal elements 18 of the fixation device 14 have beenpositioned in a desired location against the left ventricle sidesurfaces of the valve leaflets, the leaflets may then be capturedbetween the proximal elements 16 and the distal elements 18. Theproximal elements 16 are lowered toward the engagement surfaces 50 byreleasing tension from proximal element lines 90, thereby releasingproximal elements 16 so that they are then free to move, in response tothe internal spring bias force formed into proximal elements 16, from aconstrained, collapsed position to an expanded, deployed position and sothat the leaflets are held between the proximal elements 16 and thedistal elements 18. If regurgitation is not sufficiently reduced, theproximal elements 16 may be raised and the distal elements 18 adjustedor inverted to reposition the fixation device 14.

After the leaflets have been captured between the proximal and distalelements 16, 18 in a desired arrangement, the distal elements 18 may belocked to hold the leaflets LF in this position or the fixation device14 may be returned to or toward a closed position. This is achieved byretraction of the stud 74 proximally relative to coupling member 19 sothat the legs 68 of the actuation mechanism 58 apply an upwards force tothe distal elements 18 which in turn rotate the distal elements 18 sothat the engagement surfaces 50 again face one another. The releasedproximal elements 16 which are biased outwardly toward distal elements18 are concurrently urged inwardly by the distal elements 18. Thefixation device 14 may then be locked to hold the leaflets in thisclosed position. The fixation device 14 may then be released from theshaft 12. The fixation device 14 optionally includes a locking mechanismfor locking the device 14 in a particular position, such as an open,closed or inverted position or any position therebetween. The lockingmechanism may include a release harness. Applying tension to the releaseharness may unlock the locking mechanism.

The lock lines 92 engage the release harnesses 108 of the lockingmechanism 106 to lock and unlock the locking mechanism 106. The locklines 92 extend through the shaft 302 of the delivery catheter 300. Ahandle attached to the proximal end of the shaft is used to manipulateand decouple the fixation device 14.

Additional disclosure regarding such fixation devices 14 may be found inPCT Publication No. WO 2004/103162 and U.S. patent application Ser. No.14/216,787, the disclosures of both of which are incorporated herein intheir entirety.

-   -   B. Improved Grasping Mechanisms

Sometimes it can be difficult to capture or retain tissue withinfixation device 14 so that fixation device 14 approximates or repairsthe tissue as desired. Leaflet insertion may be assessed throughout theprocess of installing a fixation device 14, but it can be difficult todifferentiate good and poor leaflet insertion and retention. Forexample, when fixation device 14 is used in endovascular or minimallyinvasive procedures, visualization of the capturing or retention oftissue may be difficult.

At times during the process of installing a fixation device 14, thetissue desired to be captured or retained between proximal elements 16and distal elements 18 may seem to be securely captured or retained whenit is actually only partially captured or insecurely captured. As aresult, the free edges FE of leaflet tissue LF may later disassociatefrom the fixation device 14 and the fixation device 14 may then notproperly coapt, approximate, or repair the tissue. Even if imagingmethods make it possible to visualize when tissue is captured in thefixation device, they may not allow for a viewer to distinguish betweensecurely and insecurely captured tissue. For example, color Doppler echomay show that regurgitation has been reduced, but it may not provideprecise specifics on where along the leaflets LF fixation device 14 hascaptured the tissue, and whether the capturing is secure.

If a leaflet is poorly grasped between proximal elements 16 and distalelements 18, eventually that leaflet LF may separate from the fixationdevice 14. This may result in the fixation device 14 being attached toonly one of the leaflets LF, or separating from both leaflets LF, and nolonger functioning as desired.

In addition to difficulties arising from the imaging or visualization ofthe device 14 as it is installed, difficulty in capturing or retainingtissue within fixation device 14 may also result from the nature oftissue desired to be captured or retained. For example, when usingfixation device 14 to fix mitral valve leaflets LF to each other to stopor reduce mitral valve regurgitation, the leaflets LF are constantlymoving as the heart beats.

FIGS. 9-12 illustrate various embodiments that are intended to help afixation device 14′ capture and retain the free edges FE of leaflets LFduring placement of the fixation device 14′. To do so, these embodimentsinclude the addition of a retaining element 400 positioned on theproximal side of each distal element 18′. The retaining element 400combines with frictional elements such as barbs 410 at the lower end ofthe proximal element 16′ to capture the free edge FE of the leaflet uponits initial insertion and help retain it there until the proximal anddistal elements are fully deployed. The lower end of the proximalelement 16′ is the end closest to the stud 74′.

The retaining element 400 and barbs 410 are configured to cooperate toallow the free edge FE of the leaflets LF to easily or freely move in afirst direction toward the apex 430 formed between each proximal element16′ and the corresponding distal element 18′, but at the same time toresist or prevent movement of the free edge FE of the leaflet tissue LFin the opposite direction away from apex 430. In this way, retainingelement 400, in cooperation with the barbs 410, help to retain theleaflets LF in the device 14′ while the device is being positionedrelative to the leaflets LF and before the proximal elements 16′ anddistal elements 18′ are fully deployed.

The retaining element 400 may serve as a passive capture mechanism thatretains leaflet tissue LF without needing to be activated. For example,the retaining element 400 may retain leaflet tissue LF in the device 14′when a length of tissue of about 4-10 mm, and preferably about 6-8 mm,is located along the longitudinal axis of the distal elements 18′. Aretaining element 400 may be located on the distal elements 18′, asshown in the illustrated embodiments, or the retaining element 400 maybe located on the proximal elements 16′, or it may be located on boththe distal elements 18′ and the proximal elements 16′. A retainingelement 400 may hold a leaflet LF in place without closing the fixationelement 18′ and gripping element 16′.

As shown in FIGS. 9A-9B, in one embodiment, a retaining element 400 maybe a spring element 402 that retains leaflets LF inserted into thefixation device 14′. The spring element 402 may help capture or hold anyleaflet LF that inserts past a given point along the distal elements 18′which is determined to be sufficient insertion depth.

Referring again to FIGS. 9A-B, the spring element 402 is on a distalelement 18′. Each distal element 18′ has a spring element 402incorporated into or attached to the distal element 18′. The springelement 402 may be incorporated into or attached to the distal element18′ at a midpoint 414 between a first end 404 of the distal element 18′that attaches to a stud 74′ and the free end 406 of the distal element18′. It may also be incorporated into or attached to the distal element18′ closer to the free end 406 of each distal element 18′ or to thefirst end 404 of each distal element 18′. As shown in FIGS. 9A-B, thefixed end 412 of the spring element 402 is located between the midpoint414 and free end 406 of the distal element 18′. In addition, the springelement 402 of the retaining element 400 is elongate and can extend inan elongate fashion along substantially an entire length of the distalelement 18′ and associated distal engagement surface. Alternatively, theretaining element 400 can extend in an elongate fashion from a locationnear or adjacent first end 404 to a location distal a midpoint of thedistal engagement surface of the distal element 18′ or from a locationnear or adjacent second end 406 to a location distal a midpoint of thedistal engagement surface of the distal element 18′.

The spring element 402 may comprise a low-force leaf spring 408 biasedto push the spring element 402 towards the leaflet LF and encouragefrictional elements or barbs 410 to be deeply inserted into the leafletLF, so the leaflet LF remains in a fully seated state until distalelements 18′ are further closed. As illustrated, barbs 410 areorientated at an angle pointing toward apex 430. With barbs 410 orientedin that direction, the leading edge LE of the leaflet tissue LF isallowed to move in a first direction toward apex 430 with little or norestriction or resistance. As the leading edge LE of the leaflet tissuemoves toward apex 430, spring element 402 directs or urges the leaflettissue LF toward and into contact with barbs 410. Once the leaflettissue LF comes into contact with and engages the barbs 410, the angledorientation of the barbs 410 causes barbs 410 to penetrate into theleaflet tissue LF and then restricts or prevents movement of the leaflettissue LF in the opposite direction away from apex 430. Thus, thecombination of the retaining element 400 and the barbs 410 effectivelyfunction as a directional trap that permits the leaflet tissue LF tomove in a first direction toward apex 430 with little or no resistance,while restricting or preventing movement of the leaflet tissue LF in asecond or opposite direction away from apex 430.

The leaf spring 408 may have one or more lobes or a partial lobe. Theleaf spring 408 may be biased to allow for little to no resistance to aleaflet LF as it inserts. It may have surface features, a pointed edge,or other elements that create resistance to make it difficult for theleaflet LF to retract out. Such surface features may include, forexample, dimples, bumps, ridges, or indents. For example, as shown inFIG. 9A-B, the free end 416 of the spring element 402 may be configuredto curve toward the distal elements 18′ (as shown in FIG. 9A) whentissue LF is being trapped, and curve away from the distal element 18′(as shown in FIG. 9B) when tissue LF is being released. When the leafletis entrapped between the distal elements 18′ and the proximal elements16′, the free end 416 of the spring element 402 may be configured to lieflat against the distal element 18′.

The retaining element 400 helps the fixation device 14 capture tissuewhen proximal elements 16′ are raised and distal elements 18′ are stillpartially open. The retaining element 400 may be configured to urge theleaflet tissue against the barbs 410 on the proximal elements 16. Theretaining element 400 may be a one-way mechanism that allows tissue toenter but not exit, such as a ratchet or something similar to a ratchet.

Because repositioning and regrasping the fixation device 14′ issometimes required, the one-way mechanism should have a way for theleaflet tissue LF to be permitted to escape. The retaining element canbe designed to allow tissue to exit under certain circumstances, such aswhen the distal elements 18′ are opened to approximately 180°, as shownin FIG. 9B, or are opened even further in an inverted position, as shownin FIG. 8. Or, when the proximal elements 16′ are raised, the leaflettissue LF may be released to allow regrasping.

To ensure that the leaflets LF are properly grasped in a fixation device14′, one method of using a device with a retaining element 400 such as aspring element 402 located near each set of distal elements 18′ andproximal elements 16′ is to first capture one or both leaflets LF in thespring element 402. The spring element urges the leaflets LF against thebarbs 410 at the lower end of the proximal element 16′ to capture thefree edge FE of the leaflet LF upon its initial insertion and helpretain it there until the proximal and distal elements 16, 18 are fullydeployed. It may be possible to confirm that one or more leaflets LF iscaptured based on imaging methods such as color Doppler echo. Whenleaflets LF are trapped between the spring element 402 and the barbs410, then the proximal elements 16′ may be lowered toward the surfaces50′ of the distal elements 18′, so that the leaflets LF are heldtherebetween and the distal elements 18′ may be locked to hold theleaflets LF in this position or the fixation device 14′ may be returnedto or toward a closed position.

In another embodiment, as shown in FIG. 10, a retaining element 400comprises an arm 417. Each distal element 18′ has an arm 417incorporated into or attached to the distal element 18′. The arm 417 maybe incorporated into or attached at a fixed end 415 to the distalelement 18′ at a midpoint 414 between a first end 404 of the distalelement 18′ that attaches to a stud 74′ and the free end 406 of thedistal element 18′. It may also be incorporated into or attached to thedistal element 18′ closer to the free end 406 of each distal element 18′or to the first end 404 of each distal element 18′. As shown in FIG. 10,the fixed end 415 of the arm 417 is located between the midpoint 414 andfree end 406 of the distal element 18′.

The arm 417 has a projection or projections 418 of a suitable shape andsize to assist in retaining the leaflets LF in position. Theseprojections 418 may have sharp tips located opposite to the arm 417, orsharp edges between their tips and the arm 417. They may comprise barbshaving tapering pointed tips, scalloped edges, prongs, windings, bands,grooves, channels, bumps, surface roughening, sintering, high-frictionpads, coverings, coatings or a combination of these. As shown in FIG.10, these projections may be oriented away from the surface 50′ andangled away from the free ends 406 of the distal element 18′. They mayalso orient toward the free ends 406, or be perpendicular to the surface50′. The projections may flex or collapse toward the distal element 18′when the fixation device 14′ is closed and flex out to a fixed anglewhen the fixation device 14′ is open. For example, the projections 418may bias toward a fixed angle from the engagement surfaces 50′, but maybe pushed flat against the distal element 18′ when the distal elements18′ close around the shaft 12.

The fixation device should be configured with enough space between theproximal elements 16′ and the distal elements 18′ for a leaflet LF to beeasily inserted past the projections 418 on the distal elements 18′. Thechordal tethered leaflets LF may be tensioned lightly upon the fixationdevice 14′ just prior to closing the distal elements 18′ and proximalelements 16′. They may also be securely affixed to the device 14′ priorto closing the distal elements 18′ and proximal elements 16′.

In one embodiment, the arm 417 may be a flexible leaf-spring that pivotsat a fixed end 415 and is positioned between the proximal element 16′and distal elements 18′. It may also include a system of projections 418angled to allow entry of the tissue between the distal element 18′ andproximal element 16′, but to prevent retraction of the tissue LF. Asshown, the projection 418 and leaf spring 417 may be combined in thesame structure. In addition, the arm 417 of the retaining element 400 iselongate and can extend in an elongate fashion along substantially anentire length of the distal element 18′ and associated distal engagementsurface. Alternatively, the retaining element 400 can extend in anelongate fashion from a location near or adjacent first end 404 to alocation distal a midpoint of the distal engagement surface of thedistal element 18′ or from a location near or adjacent second end 406 toa location distal a midpoint of the distal engagement surface of thedistal element 18′.

As shown in FIG. 11, in another embodiment the retaining element 400 maycomprise one or more protrusions 420. One or more protrusions 420 may bepositioned close to the hinge point of the distal elements 18′ on theengagement surface 50′. When a leaflet LF is inserted past theprotrusion 420, the protrusion 420 may reduce leaflet detachment upondeployment of the fixation device 14′ by directing or urging the leafletLF into contact with the gripping surfaces or barbs 410 located on theopposing proximal element 16′. The protruding feature 420 may be locatednear a midpoint 414 between a first end 404 of the distal element 18′that attaches to a stud 74′ and the free end 406 of the distal element18′. It may also be incorporated into or attached to the distal element18′ closer to the free end 406 of each distal element 18′ or to thefirst end 404 of each distal element 18′. A protruding feature 420 maybe a rigid piece of material that is affixed to the engagement surface50′ of distal elements 18′ and may be atraumatic to aid with directingor urging the leaflet LF while causing minimal damage to the leaflet LF,such as not penetrating or puncturing the leaflet LF. The protrudingfeature may be comprised of any biocompatible material or materials,such as a polymer, nitinol, or other alloys, or bioabsorbable materials.

The protruding feature 420 of the distal elements 18′ may passivelyengage the leaflet tissue LF when leaflet tissue LF is sufficientlyinserted into the device 14′. Or, the protruding feature 420 may beconfigured to help engage leaflet tissue and secure it into positionwhen the proximal elements 16′ are lowered and also secure the leaflettissue LF. The protruding feature 420 may help entrap tissue between theprotruding feature 420 and the gripping surfaces of the proximalelements 16′. The feature 420 may urge the tissue LF against the barbs410.

While the protruding feature 420 is illustrated as including a generallycurved or domed outer surface, it will be understood that various othersurface orientations are appropriate while maintaining the atraumaticnature and ability to aid with directing or urging the leaflet LF. Forinstance, as illustrated in FIGS. 11B-11E, the protruding feature 420can have a curved surface that is symmetric or asymmetric in (i) adirection from first end 404 towards the second end 406. (ii) adirection cross-wise, transverse, or oblique to the direction from firstend 404 towards the second end 406, or (iii) both. So the protrudingfeature 420 can be symmetric in at least one axis, at least two axes, orin all three axes. Alternatively, the protruding feature 420 can beasymmetric in at least one axis, at least two axes, or in all threeaxes.

In another embodiment, shown in FIG. 12, the retaining element 400 maycomprise a hinge 422 that is attached to the surface 50′ of the distalelements 18′. The hinge 422 connects to an arm 424 that can swing towardand away from the distal element 18′. As shown in FIG. 12, the arm 424may bias toward the first end 404 of each distal element 18′. The arm424 may be capable of laying parallel to or flat against the surface 50′while being oriented toward the first end 404 of the distal element 18′.It also may be capable of laying parallel to or flat against the surface50′ while being oriented toward the free end 406 of the distal element18′, and therefore capable of rotating 180°. The hinge 422 may restrictthe movement of the arm 424 so that it can, for example, only lieparallel to the surface 50′ while being oriented toward the first end404 of the distal element 18′ and be rotated about 90°, so that theangle formed between the arm 424 and the portion of the distal element18′ below the hinge 422 can be no greater than 90°. The hinge 422 mayalso be a pivoting element.

There may also be multiple arms 424 on the distal element 18′. Forexample, there may be two arms, each located the same distance betweenthe ends 404 and 406, and positioned next to each other on theengagement surface 50′. If there are multiple retaining elements 400,such as multiple arms 424 or multiple spring elements 402, they may beconfigured to be positioned on either side of the barbs 410 on theproximal element. Retaining element or elements 400 may also bepositioned to be located between barbs 410 on the proximal element 16′,if there are multiple barbs 410 on the proximal element 16′. Inaddition, the arm 424 of the retaining element 400 is elongate and canextend in an elongate fashion along substantially an entire length ofthe distal element 18′ and associated distal engagement surface.Alternatively, the retaining element 400, and associated arm 424, canextend in an elongate fashion from a location near or adjacent first end404 to a location distal a midpoint of the distal engagement surface ofthe distal element 18′ or from a location near or adjacent second end406 to a location distal a midpoint of the distal engagement surface ofthe distal element 18′.

The distal elements 18 may be covered with a fabric or other flexiblematerial. Preferably, when fabrics or coverings are used in combinationwith projections 418, such features will protrude through such fabric orother covering so as to contact the leaflet tissue LF.

Analogous to a mechanical pawl, the bias, angle, and direction of aretaining element 400 may allow the leaflet to fall or slide deepertowards the stud 74′ without much resistance but may restrict theability of the leaflet LF to move back out. By permitting the leaflet LFto easily enter but not permitting it to easily be removed from thefixation device 14′, this may help entrap the leaflet LF in a fullyinserted state.

In the embodiments described above, the retaining element 400 is apassive element. However, retaining element 400 may also include anactive element such that, when a piece of leaflet tissue LF proceedsbeyond or next to a portion of the retaining element 400, the retainingelement 400 may automatically spring or deploy in such a way as toretain tissue LF in place.

In another embodiment, a fixation device 14 or 14′ may comprise amechanical or physical sensor or some visual indicator of when a leafletis properly inserted into the device prior to closing the distalelements 18′ and deployment of the fixation device 14 or 14′. Forexample, a tactile sensor may be embedded near the first end 404 of eachdistal element. Each tactile sensor may provide a signal or indicationwhen the leaflet LF touches the sensor, and the sensor may be located sothat the leaflet LF will be unable or unlikely to touch the sensorunless the leaflet is adequately captured.

Yet another mechanism for enhancing the placement and retention of theleaflet tissue LF in the fixation device 14 or 14′ is to facilitateactuation of each proximal element 16 or 16′ and each distal element 18or 18′ independent from one another. When the proximal elements 16 or16′ for both leaflets LF are activated simultaneously, and the distalelements 18 or 18′ for each leaflet LF are also activatedsimultaneously, it can be hard to capture both leaflets, because it isnecessary to capture both at the same time. In other words, when theactivation of both proximal elements 16 or 16′ is symmetric, and theactivation of both distal elements 18 or 18′ is symmetric, the fixationdevice 14 or 14′ is not able to grasp one leaflet first and then theother. If a catheter or the fixation device 14 or 14′ is not properlypositioned, or if either leaflet LF has redundant or loose length, thefixation device 14 or 14′ may not fully seat the leaflets between eachdistal fixation element 18 or 18′ and proximal gripping element 16 or16′.

In one embodiment, each proximal element 16 or 16′ and/or each distalelement 18 or 18′ may be activated independently from each other. Forexample, there may be a separate proximal element line for each proximalelement 16 or 16′. Similarly, there may be two actuator rods 64 whichextend through the shaft 12, each of which may be configured to activateone distal element 18 or 18′.

In addition to being used to repair mitral valves, these devices can beused in a variety of therapeutic procedures, including endovascular,minimally-invasive, and open surgical procedures, and can be used invarious anatomical regions, including abdominal, thoracic,cardiovascular, intestinal, digestive, respiratory, and urinary systems,and other systems and tissues. The invention provides devices, systems,and methods that may more successfully approximate and repair tissue byimproving the capture of tissue into the devices.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

What is claimed is:
 1. A device for fixation of leaflets of a heartvalve comprising: a delivery catheter having a distal end; and afixation implant releasably attached to the distal end, the fixationimplant comprising: first and second distal elements moveable between anopen position and a closed position, each distal element extendingoutwardly from a center of the fixation implant in the open position; afirst retaining element extending from the first distal element towardthe center of the fixation implant in the open position to preliminarilyengage a first leaflet of the heart valve; a second retaining elementextending from the second distal element toward the center of thefixation implant in the open position to preliminarily engage a secondleaflet of the heart valve; a first proximal element movable to capturethe first leaflet of the heart valve between the first proximal elementand the first retaining element; and a second proximal element moveableto capture the second leaflet of the heart valve between the secondproximal element and the second retaining element, wherein the firstretaining element is located between the first distal element and thefirst proximal element in the closed position, and the second retainingelement is located between the second distal element and the secondproximal element in the closed position, and further wherein the firstand second distal elements are configured to cover the first and secondretaining elements, respectively, in the closed position.
 2. The deviceof claim 1, wherein the first retaining element extends at least to alocation distal a midpoint of the first distal element, and the secondretaining element extends at least to a location distal a midpoint ofthe second distal element.
 3. The device of claim 1, wherein the firstretaining element is pivotally coupled to the first distal element andthe second retaining element is pivotally coupled to the second distalelement.
 4. The device of claim 1, wherein the first retaining elementis configured to pivot up to 180 degrees relative to the first distalelement and the second retaining element is configured to pivot up to180 degrees relative to the second distal element.
 5. The device ofclaim 1, wherein each proximal element includes a plurality of frictionelements.
 6. The device of claim 5, wherein the plurality of frictionelements comprises a plurality of barbs.
 7. The device of claim 5,wherein each of the first and second retaining elements is configured tocooperate with the plurality of friction elements of the respectiveproximal element to allow a leading free edge of the first leaflet ofthe heart valve and the second leaflet of the heart valve, respectively,to move freely in a first direction toward the center of the fixationimplant and to restrict movement of the free edge of the respectivefirst and second leaflet of the heart valve in a second directionopposite the first direction.
 8. The device of claim 1, furthercomprising at least two sutures configured to raise and lower the firstand second proximal elements relative the first and second retainingelements, respectively.
 9. The device of claim 1, wherein each of thefirst and second distal elements includes a fabric covering.
 10. Thedevice of claim 9, wherein each of the first and second distal elementshas a concave surface.
 11. The device of claim 10, wherein the concavesurfaces of the first and second distal elements are configured tosurround a central portion of the fixation implant in the closedposition.
 12. The device of claim 11, wherein the central portion has alongitudinal axis defining the center of the fixation implant.
 13. Thedevice of claim 1, wherein each of the first and second distal elementshas an outwardly extending end in the open position, and wherein each ofthe first and second retaining elements is attached to the respectivefirst and second distal element near the corresponding outwardlyextending end.
 14. The device of claim 1, further comprising a hingebetween each of the first and second retaining elements and therespective first and second distal element.
 15. The device of claim 14,wherein each of the first and second retaining element can swing towardand away from the respective first and second distal element about thecorresponding hinge.
 16. The device of claim 14, wherein each of thefirst and second retaining elements is capable of rotating 180 degreesabout the corresponding hinge.
 17. The device of claim 1, wherein eachof the first and second retaining elements is capable of being alignedparallel with the respective first and second distal element in theclosed position.
 18. A fixation implant for fixation of leaflets of aheart valve comprising: first and second distal elements moveablebetween an open position and a closed position, each distal elementextending outwardly from a center of the fixation implant in the openposition; a first retaining element extending from the first distalelement toward the center of the fixation implant in the open positionto preliminarily engage a first leaflet of the heart valve; a secondretaining element extending from the second distal element and thecenter of the fixation implant in the open position to preliminarilyengage a second leaflet of the heart valve; a first proximal elementmovable to capture the first leaflet of the heart valve between thefirst proximal element and the first retaining element; and a secondproximal element moveable to capture the second leaflet of the heartvalve between the second proximal element and the second retainingelement, wherein the first retaining element is located between thefirst distal element and the first proximal element in the closedposition, and the second retaining element is located between the seconddistal element and the second proximal element in the closed position,and further wherein the first and second distal elements are configuredto cover the first and second retaining elements, respectively, in theclosed position.
 19. A fixation implant for fixation of leaflets of aheart valve comprising: first and second distal elements moveablebetween an open position and a closed position, each distal elementincluding a fabric covering and defining a concave shape, each distalelement extending outwardly from a center of the fixation implant whenin the open position; a first retaining element extending from the firstdistal element in the open position to preliminarily engage a firstleaflet of the heart valve, wherein the first retaining element isdisposed within the concave shape of the first distal element when inthe closed position; a second retaining element extending from thesecond distal element in the open position to preliminarily engage asecond leaflet of the heart valve, wherein the second retaining elementis disposed within the concave shape of the second distal element whenin the closed position; a first proximal element movable to capture thefirst leaflet of the heart valve between the first proximal element andthe first retaining element; and a second proximal element moveable tocapture the second leaflet of the heart valve between the secondproximal element and the second retaining element, wherein the firstretaining element is located between the first distal element and thefirst proximal element in the closed position, and the second retainingelement is located between the second distal element and the secondproximal element in the closed position.